Hydrocarbon oil treatment



Patented Mar. 17, 1936 A'EENT OFFIE HYDROCARBON OIL TREATMENT Seymour W. Ferris, Aldan, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Application March 14, 1933,

Serial No. 660,650

18 Claims.

The present invention relates to the art of mineral oil refining, and has particular reference to the separation of crude petroleum or petroleum products into fractions of different chemical compositions while of approximately the same distillation range.

In accordance with my invention, crude petroleum or petroleum products, particularly oils of substantial viscosity, are separated into various fractions by means of fractional extraction with an unsaturated aliphatic alcohol, and more particularly allyl alcohol or a mixture of solvents containing substantial amounts of unsaturated aliphatic alcohols. The term unsaturated aliphatic alcohol as used herein comprehends one or a mixture of two or more unsaturated aliphatic alcohols, Specific examples of other unsaturated aliphatic alcohols that may be employed in my process are crotonyl alcohol and dimethyl allyl carbinol.

It is recognized in the art that mineral oils,

such as petroleum, comprise essentially a mixture of hydrocarbons of various groups or homologous series of compounds, such for example, as paraffins of the general formula CnH2n+2, olefines of the general formula 011E211; hydroaromatics and polymethylenes of the same empirical formula, and various other series of compounds of chain and/or ring structures in which the hydrogen to carbonratio is less than in the foregoing series. A large number of individual compounds'o-f each series and of differing boiling points are present in petroleum.

The various types of crude'petroleum, which are generally classified into three groups, namely, paraflinic base, naphthenic or asphaltic base, and

a mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. For example, in the paraffin base crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the naphthenic or asphaltic base crude oils, there is a relatively large proportion of hydrocarbons having ring structures and a low hydrogen to carbon ratio. Mixed base crude oils, such as are obtained from the Mid-Continent oil fields, contain hydrocarbons in proportions intermediate these two extremes.

The variance in the proportion of the different series of'hydrocarbons in parafiinic, naphthenic,

and mixed base oils is evidenced by the physical properties of the various oils and particularly by the relationship of the specific gravity to the 1 viscosity of one oil as comparedwith another.

For example, oils derived from a Pennsylvania stant as hereinafter described.

If a given crude petroleum be distilled into successive fractions and the'specific gravities and viscosities of the several viscous fractions be determined, it will be found that they conform to the general relationship expressed by the formulae 0.755a+ 0.022 log (V 35.5),

in which G is the specific gravity at F., V and V are respectively Saybolt universal viscosities at F. and 210 F., and a is a constant known as the viscosity-gravity constant; Viscous fractions from each of the different types of crude have different viscosity-gravity constants. While, in general, viscous fractions from a single crude have substantially the same viscositygravity constant, such constant is lower for fractions of the paraffinic crudes than isthe constant for fractions of the naphthenic crudes. An article entitled The viscosity-gravity constant of petroleum lubricating oils by J. B. Hill and H. B. coats, which will be found in volume 20,-page 641 et seq., Industrial and Engineering Chemistry for June, 1923, explains the determination of such constant for several typical oils.

The viscosity-gravity constant is, therefore, an. index of the paraifinicity or naphthenicity of viscous oils, since when a given crude is distilled, the fractions thereof collected, and the specific gravity and the viscosity of each of the viscous fractions determined, such specific gravities and viscosities substituted in the formula, and the viscosity-gravity constants of the fractions calculated, it will be found that such constants are substantially the same.

The viscosity-gravity constants of the viscous fractions for some of the typical crudes are as follows:

Milltown (Pennsylvania) 0.8067 Burbank (Mid-Continent) 0.8367 Guadalupe (Gulf Coast) 0.8635 Mirando (Gulf Coast) 0.9025

While the above figures indicate the viscositygravity constants of specific oils from several types of crudes, it is to be understood that for any particular type of crude such constant may be within a range between values above and below the constant of the typical crude given. For example, viscous oils resulting from the distillation of Mid-Continent crudes have viscositygravity constants ranging from about .835 to about .855, whereas the viscous fractions resulting from the distillation of Pennsylvania type crudes range from about .805 to about .828, and in most instances, are below .820. Oils are increasingly paraflinic as their viscosity-gravity constants decrease.

My invention is based upon the discovery that oils containing both the paraifinic series of hydrocarbons and the various naphthenic series may be fractionally extracted with an unsaturated aliphatic alcohol. The various series of hydrocarbons possess a differential solubility in such solvent, the naphthenic hydrocarbons being much more soluble therein than the paraflinic hydrocarbons. By means of extraction with such solvent, it is therefore possible to effect a partial separation of the naphthenic hydrocarbons from the parafiinic, and to obtain from an oil containing both classes of hydrocarbons, an oil which is much more paraifinic than the original oil and one which is much more naphthenic. By my invention, for example, it is possible to produce an oil of the quality normally obtained from Appalachian crudes, from crudes of the mixed base type from the Mid-Continent area, and, conversely, to obtain oils from mixed base crudes such as are normally obtained from the naphthenic oils of the Gulf Coast area. In general, from oils from any source there may be obtained by :my process, oils which are respectively more parafiinic and more naphthenic than the oils normally obtained from such source by distillation.

In accordance with my invention, I first mix the oil to be treated with a suitable proportion of the solvent at a temperature such that complete solution is effected and a homogeneous liquid obtained. I then cool the mixture .to a temperature at which separation of the liquid into a two-layer system will take place. The upper layer will contain a relatively small amount of the solvent dissolved in the parafiinic portion of the oil while the lower layer will contain the more naphthenic portion of the oil dissolved in the solvent. Or, I may agitate the mixture of solvent and oil at temperatures at which the liquids are only partially miscible, and thereby efiect solution of the naphthenic portion of the oil in the solvent. In either of the above procedures I may take advantage of the principles of countercurrent extraction.

After the extraction proper, I efi'ect separation of the two layers which form, by any suitable procedure, as for example, by decantation. I then remove from each of the separated layers, the portion of solvent which each contains by suitable procedure, such as by vacuum distillation, thereby to obtain two oils of similar distillation ranges but of different chemical compositions and different physical characteristics.

Before removing the solvent from the upper and more parafiinic layer, I may add a further quantity of solvent and repeat the extraction, thereby to remove additional naphthenic constituents from said layer. The extraction step may be repeated any desired number of times, each repetition producing an oil of higher paraffinicity as evidenced by its lower viscosity-gravity constant.

, Where substantial quantities of waxy hydrocarbons belonging to the true parafiin series (CnH2n+z) arepresent, such hydrocarbons remain in the upper or more parafiinic layer and may cause such layer to be solid or semi-solid. Such layer may be separated into solid and liquid hydrocarbons by any of the well-known dewaxing processes such as by cold-settling or by centrifuging. In many instances it may be advantageous to dewax the oil prior to extraction. However, it is to be understood that in accordance with my invention, dewaxing may be effected either prior or subsequent to extraction.

My invention will be further understood from the following specific examples:

100 parts of a Gulf Coast distillate having a viscosity of 612 seconds Saybolt universal at 100 R, an A. P. I. gravity of 206 at F., and a viscosity-gravity constant of 0.874 was mixed with 300 parts of allyl alcohol and heated to slightly above the temperature of complete miscibility. The homogeneous liquid which resulted was cooled with agitation to F. and allowed to settle whereupon a two layer system formed. After separation, the layers were each freed of solvent by vacuum distillation. The undissolved oil fraction comprising 47% of the stock had a viscosity of 401 seconds Saybolt universal at 100 F., and A. P. I. gravity of 241, and a viscosity-gravity constant of 0.852. The dissolved oil fraction comprising 53% of the stock had a viscosity of 63 seconds Saybolt universal at 210 F., and A. P. I. gravity of 17.4", and a viscosity-gravity constant of 0.899.

100 parts of a Mid-Continent distillate having a viscosity of 305 seconds Saybolt universal at 100 and A. P. I. gravity of 242 at 60 F., and a viscosity-gravity constant of 0.853 was mixed with 740 parts of allyl alcohol and heated to slightly above the temperature of complete missibility, which was approximately 95 C. The homogeneous liquid which resulted was cooled with agitation to C. and allowed to settle, whereupon a two layer system formed. After separation, the layers were each freed of solvent by vacuum distillation. The undissolved oil fraction comprising 20% of the stock had a viscosity of 264 seconds Saybolt universal at 100 F., and A. P. I. gravity of 28.4, and a viscosity-gravity constant of 0.826. The dissolved oil fraction comprising of the stock had a viscosity of 350 seconds Saybolt universal at F., and A. P. I. gravity of 234 and a viscosity-gravity constant of 0.861.

From the above examples it will be noted that by extraction of an oil with allyl alcohol, there may be obtained oil fractions which are respectively more parafiinic and more naphthenic than the original oil. By repetition of the extraction process upon the undissolved fraction, oils of even greater paraffinicity will result.

My process is practically independent of the particular nature or source of the crude oil or oil fraction to be extracted. There may be produced by my process oil products of desired characteristics from oils which by distillation will not produce such products.

'Hereinabove, mixtures of solvents have been referred to. It is to beunderstood that in such mixtures the constituents will not react with one another nor with the oil upon which they are to be used, and that such mixtures will contain substantial amounts of an unsaturated aliphatic alcohol.

For brevity, in the appended claims unsaturated aliphatic alcohol is employed, in a generic sense to include one or a mixture of unsaturated aliphatic alcohols or a mixture of solvents containing substantial amounts of unsaturated aliphatic alcohols.

Also, where herein and in the appended claims, oil is specifically referred to as being viscous, it is to be understood that the oil is of substantial viscosity, i. e., of the order of seconds Saybolt universal at 100 F., or more.

What I claim is:

1. In the art of refining mineral oils, the process which comprises separating an oil containing parafiinic and naphthenic hydrocarbons into fractions respectively richer in paraifinic and naphthenic compounds by extracting said oil with an unsaturated aliphatic alcohol.

2. In the art of refining mineral oils, the process which comprises adding an unsaturated aliphatic alcohol to an oil containing paraffinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to form a two-layer system, and separating the upper layer from the lower layer.

3. In the art of refining mineral oils, the process which comprises adding an unsaturated aliphatic alcohol to an oil containing paraflinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to form a two layer system, removing the lower layer, and similarly retreating the upper layer with an unsaturated aliphatic alcohol.

4. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing paraffinic and naphthenic hydrocarbons into contact with an unsaturated aliphatic alcohol, thereby to effect solution of a portion richer in naphthenic hydrocarbons in the unsaturated aliphatic alcohol, separating the solution so formedfrom the remainder of the oil, and removing the unsaturated aliphatic alcohol from both portions of the oil, thereby to obtain fractions of the oil respectively richer in paraflinic and naphthenic hydrocarbons.

5. The process for separating mineral oils containing parafiinic and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with an unsaturated aliphatic alcohol, thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the unsaturated aliphatic alcohol, separating the solution so formed from the remainder of the oil, and distilling the unsaturated aliphatic alcohol from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiini'c and naphthenic hydrocarbons.

6. In the art of refining mineral oils, the process which comprises bringing a mineral oil condistilling the crude and bringing a portion thereof into contact with allyl alcohol, thereby partially dissolving the oil, separating the allyl alcohol solution of oil so treated, and removing the allyl alcohol from the treated oil.

8. In the art of refining mineral lubricating oil containing parafiim'c and naphthenic hydrocarbons, the step of fractionally extracting the oil with allyl alcohol, to effect a separation of fractions respectively richer in parafiinic and naphthenic compounds.

9. The process of treating a viscous fraction oi. a crude oil of one type containing parafiinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a greater 'content of paraffinic hydrocarbons, which comprises extracting the viscous fraction with allyl alcohol, and separating the oil so treated into portions respectively richer in parafiinic and naphthenic hydrocarbons.

10. The process of treating a viscous fraction of a mixed base crude oil to procure a fraction having the quality of a corresponding fraction of a paraffinic base crude, which comprises extracting the viscous fraction with allyl alcohol, and separating the oil so treated into portions respectively richer in paraifinic and naphthenic compounds.

11. In the art of refining mineral oils, the process which comprises adding allyl alcohol to a viscous oil liquid at ordinary temperatures containing parafiinic and naphthenic hydrocarbons, heating the mixture to a temperature sufficient to effect solution, cooling the solution to a temperature sufficient to form two layers respectively richer in naphthenic hydrocarbons and paraflinic hydrocarbons other than wax, and separating the upper layer richer in par-afiinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

12. In the art of refining mineral oils, the process which comprises adding allyl alcohol to a viscous oil liquid at ordinary temperatures containing parailinic and naphthenic hydrocarbons, heating the mixture to a temperature sufiicient to efiect solution, cooling the solution to a temperature suificient to form two layers, separating the allyl alcohol and paraffin wax from the upper layer, and separating the allyl alcohol from the lower layer to produce one fraction richer in parafiini'c and a second fraction richer in naphthenic hydrocarbons than said viscous oil.

13. In the art of refining mineral oils, the proc-- ess which comprises bringing allyl alcohol into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing paraffinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania type crude by distillation.

14. The process of decreasing the viscositygravity constant of a viscous mineral oil which comprises extracting the oil with an unsaturated aliphatic alcohol.

15. The process of decreasing the viscositygravity constant of a viscous mineral oil at least 0.015 which comprises extracting the oil with allyl alcohol. 7 16. The process of treating a viscous mineral oil of viscosity-gravity constant between substantially 0.850 and 0.875 to reduce the viscositygravity constant by at least 0.015, which comprises fractionally extracting said viscous oil with allyl alcohol.

17. The process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.850 to produce an oil having a viscosity-gravity constant less than 0.830 which comprises fractionally extracting said viscous oil with allyl alcohol.

18. The process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.835 to produce an oil having a viscosity-gravity constant of less than 0.828 which comprises fractionally extracting said viscous oil with allyl alcohol.

SEYMOUR W. FERRIS. 

